aom_dsp/arm/aom_convolve8_neon_dotprod.c - aom - Git at Google

 /*
  * Copyright (c) 2014 The WebM project authors. All rights reserved.
  * Copyright (c) 2023, Alliance for Open Media. All rights reserved.
  *
  * This source code is subject to the terms of the BSD 2 Clause License and
  * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
  * was not distributed with this source code in the LICENSE file, you can
  * obtain it at www.aomedia.org/license/software. If the Alliance for Open
  * Media Patent License 1.0 was not distributed with this source code in the
  * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
  */

 #include <arm_neon.h>
 #include <assert.h>
 #include <string.h>

 #include "config/aom_config.h"
 #include "config/aom_dsp_rtcd.h"

 #include "aom/aom_integer.h"
 #include "aom_dsp/aom_dsp_common.h"
 #include "aom_dsp/aom_filter.h"
 #include "aom_dsp/arm/aom_convolve8_neon.h"
 #include "aom_dsp/arm/aom_filter.h"
 #include "aom_dsp/arm/mem_neon.h"
 #include "aom_dsp/arm/transpose_neon.h"
 #include "aom_ports/mem.h"

 // Filter values always sum to 128.
 #define FILTER_WEIGHT 128

 DECLARE_ALIGNED(16, static const uint8_t, kDotProdPermuteTbl[48]) = {
   0, 1, 2,  3,  1, 2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6,
   4, 5, 6,  7,  5, 6,  7,  8,  6,  7,  8,  9,  7,  8,  9,  10,
   8, 9, 10, 11, 9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14
 };

 DECLARE_ALIGNED(16, static const uint8_t, kDotProdMergeBlockTbl[48]) = {
   // Shift left and insert new last column in transposed 4x4 block.
   1, 2, 3, 16, 5, 6, 7, 20, 9, 10, 11, 24, 13, 14, 15, 28,
   // Shift left and insert two new columns in transposed 4x4 block.
   2, 3, 16, 17, 6, 7, 20, 21, 10, 11, 24, 25, 14, 15, 28, 29,
   // Shift left and insert three new columns in transposed 4x4 block.
   3, 16, 17, 18, 7, 20, 21, 22, 11, 24, 25, 26, 15, 28, 29, 30
 };

 static inline int16x4_t convolve8_4_h(const uint8x16_t samples,
                                       const int8x8_t filters,
                                       const uint8x16x2_t permute_tbl) {
   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t samples_128 =
       vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

   // Permute samples ready for dot product.
   // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
   // { 4,  5,  6,  7,  5,  6,  7,  8,  6,  7,  8,  9,  7,  8,  9, 10 }
   int8x16_t perm_samples[2] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
                                 vqtbl1q_s8(samples_128, permute_tbl.val[1]) };

   // Accumulate into 128 * FILTER_WEIGHT to account for range transform.
   // (Divide by 2 since we halved the filter values.)
   int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
   int32x4_t sum = vdotq_lane_s32(acc, perm_samples[0], filters, 0);
   sum = vdotq_lane_s32(sum, perm_samples[1], filters, 1);

   // Further narrowing and packing is performed by the caller.
   return vmovn_s32(sum);
 }

 static inline uint8x8_t convolve8_8_h(const uint8x16_t samples,
                                       const int8x8_t filters,
                                       const uint8x16x3_t permute_tbl) {
   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t samples_128 =
       vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

   // Permute samples ready for dot product.
   // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
   // { 4,  5,  6,  7,  5,  6,  7,  8,  6,  7,  8,  9,  7,  8,  9, 10 }
   // { 8,  9, 10, 11,  9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14 }
   int8x16_t perm_samples[3] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
                                 vqtbl1q_s8(samples_128, permute_tbl.val[1]),
                                 vqtbl1q_s8(samples_128, permute_tbl.val[2]) };

   // Accumulate into 128 * FILTER_WEIGHT to account for range transform.
   // (Divide by 2 since we halved the filter values.)
   int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
   // First 4 output values.
   int32x4_t sum0 = vdotq_lane_s32(acc, perm_samples[0], filters, 0);
   sum0 = vdotq_lane_s32(sum0, perm_samples[1], filters, 1);
   // Second 4 output values.
   int32x4_t sum1 = vdotq_lane_s32(acc, perm_samples[1], filters, 0);
   sum1 = vdotq_lane_s32(sum1, perm_samples[2], filters, 1);

   // Narrow and re-pack.
   int16x8_t sum = vcombine_s16(vmovn_s32(sum0), vmovn_s32(sum1));
   // We halved the filter values so -1 from right shift.
   return vqrshrun_n_s16(sum, FILTER_BITS - 1);
 }

 static inline void convolve8_horiz_8tap_neon_dotprod(
     const uint8_t *src, ptrdiff_t src_stride, uint8_t *dst,
     ptrdiff_t dst_stride, const int16_t *filter_x, int w, int h) {
   // Filter values are even, so halve to reduce intermediate precision reqs.
   const int8x8_t filter = vshrn_n_s16(vld1q_s16(filter_x), 1);

   if (w == 4) {
     const uint8x16x2_t perm_tbl = vld1q_u8_x2(kDotProdPermuteTbl);
     do {
       uint8x16_t s0, s1, s2, s3;
       load_u8_16x4(src, src_stride, &s0, &s1, &s2, &s3);

       int16x4_t d0 = convolve8_4_h(s0, filter, perm_tbl);
       int16x4_t d1 = convolve8_4_h(s1, filter, perm_tbl);
       int16x4_t d2 = convolve8_4_h(s2, filter, perm_tbl);
       int16x4_t d3 = convolve8_4_h(s3, filter, perm_tbl);
       // We halved the filter values so -1 from right shift.
       uint8x8_t d01 = vqrshrun_n_s16(vcombine_s16(d0, d1), FILTER_BITS - 1);
       uint8x8_t d23 = vqrshrun_n_s16(vcombine_s16(d2, d3), FILTER_BITS - 1);

       store_u8x4_strided_x2(dst + 0 * dst_stride, dst_stride, d01);
       store_u8x4_strided_x2(dst + 2 * dst_stride, dst_stride, d23);

       src += 4 * src_stride;
       dst += 4 * dst_stride;
       h -= 4;
     } while (h > 0);
   } else {
     const uint8x16x3_t perm_tbl = vld1q_u8_x3(kDotProdPermuteTbl);

     do {
       int width = w;
       const uint8_t *s = src;
       uint8_t *d = dst;
       do {
         uint8x16_t s0, s1, s2, s3;
         load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

         uint8x8_t d0 = convolve8_8_h(s0, filter, perm_tbl);
         uint8x8_t d1 = convolve8_8_h(s1, filter, perm_tbl);
         uint8x8_t d2 = convolve8_8_h(s2, filter, perm_tbl);
         uint8x8_t d3 = convolve8_8_h(s3, filter, perm_tbl);

         store_u8_8x4(d, dst_stride, d0, d1, d2, d3);

         s += 8;
         d += 8;
         width -= 8;
       } while (width != 0);
       src += 4 * src_stride;
       dst += 4 * dst_stride;
       h -= 4;
     } while (h > 0);
   }
 }

 static inline int16x4_t convolve4_4_h(const uint8x16_t samples,
                                       const int8x8_t filters,
                                       const uint8x16_t permute_tbl) {
   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t samples_128 =
       vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

   // Permute samples ready for dot product.
   // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
   int8x16_t perm_samples = vqtbl1q_s8(samples_128, permute_tbl);

   // Accumulate into 128 * FILTER_WEIGHT to account for range transform.
   // (Divide by 2 since we halved the filter values.)
   int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
   int32x4_t sum = vdotq_lane_s32(acc, perm_samples, filters, 0);

   // Further narrowing and packing is performed by the caller.
   return vmovn_s32(sum);
 }

 static inline uint8x8_t convolve4_8_h(const uint8x16_t samples,
                                       const int8x8_t filters,
                                       const uint8x16x2_t permute_tbl) {
   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t samples_128 =
       vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

   // Permute samples ready for dot product.
   // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
   // { 4,  5,  6,  7,  5,  6,  7,  8,  6,  7,  8,  9,  7,  8,  9, 10 }
   int8x16_t perm_samples[2] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
                                 vqtbl1q_s8(samples_128, permute_tbl.val[1]) };

   // Accumulate into 128 * FILTER_WEIGHT to account for range transform.
   // (Divide by 2 since we halved the filter values.)
   int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
   // First 4 output values.
   int32x4_t sum0 = vdotq_lane_s32(acc, perm_samples[0], filters, 0);
   // Second 4 output values.
   int32x4_t sum1 = vdotq_lane_s32(acc, perm_samples[1], filters, 0);

   // Narrow and re-pack.
   int16x8_t sum = vcombine_s16(vmovn_s32(sum0), vmovn_s32(sum1));
   // We halved the filter values so -1 from right shift.
   return vqrshrun_n_s16(sum, FILTER_BITS - 1);
 }

 static inline void convolve8_horiz_4tap_neon_dotprod(
     const uint8_t *src, ptrdiff_t src_stride, uint8_t *dst,
     ptrdiff_t dst_stride, const int16_t *filter_x, int width, int height) {
   const int16x4_t x_filter = vld1_s16(filter_x + 2);
   // All 4-tap and bilinear filter values are even, so halve them to reduce
   // intermediate precision requirements.
   const int8x8_t filter = vshrn_n_s16(vcombine_s16(x_filter, vdup_n_s16(0)), 1);

   if (width == 4) {
     const uint8x16_t permute_tbl = vld1q_u8(kDotProdPermuteTbl);

     do {
       uint8x16_t s0, s1, s2, s3;
       load_u8_16x4(src, src_stride, &s0, &s1, &s2, &s3);

       int16x4_t t0 = convolve4_4_h(s0, filter, permute_tbl);
       int16x4_t t1 = convolve4_4_h(s1, filter, permute_tbl);
       int16x4_t t2 = convolve4_4_h(s2, filter, permute_tbl);
       int16x4_t t3 = convolve4_4_h(s3, filter, permute_tbl);
       // We halved the filter values so -1 from right shift.
       uint8x8_t d01 = vqrshrun_n_s16(vcombine_s16(t0, t1), FILTER_BITS - 1);
       uint8x8_t d23 = vqrshrun_n_s16(vcombine_s16(t2, t3), FILTER_BITS - 1);

       store_u8x4_strided_x2(dst + 0 * dst_stride, dst_stride, d01);
       store_u8x4_strided_x2(dst + 2 * dst_stride, dst_stride, d23);

       src += 4 * src_stride;
       dst += 4 * dst_stride;
       height -= 4;
     } while (height > 0);
   } else {
     const uint8x16x2_t permute_tbl = vld1q_u8_x2(kDotProdPermuteTbl);

     do {
       const uint8_t *s = src;
       uint8_t *d = dst;
       int w = width;

       do {
         uint8x16_t s0, s1, s2, s3;
         load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

         uint8x8_t d0 = convolve4_8_h(s0, filter, permute_tbl);
         uint8x8_t d1 = convolve4_8_h(s1, filter, permute_tbl);
         uint8x8_t d2 = convolve4_8_h(s2, filter, permute_tbl);
         uint8x8_t d3 = convolve4_8_h(s3, filter, permute_tbl);

         store_u8_8x4(d, dst_stride, d0, d1, d2, d3);

         s += 8;
         d += 8;
         w -= 8;
       } while (w != 0);
       src += 4 * src_stride;
       dst += 4 * dst_stride;
       height -= 4;
     } while (height > 0);
   }
 }

 void aom_convolve8_horiz_neon_dotprod(const uint8_t *src, ptrdiff_t src_stride,
                                       uint8_t *dst, ptrdiff_t dst_stride,
                                       const int16_t *filter_x, int x_step_q4,
                                       const int16_t *filter_y, int y_step_q4,
                                       int w, int h) {
   assert((intptr_t)dst % 4 == 0);
   assert(dst_stride % 4 == 0);

   (void)x_step_q4;
   (void)filter_y;
   (void)y_step_q4;

   src -= ((SUBPEL_TAPS / 2) - 1);

   int filter_taps = get_filter_taps_convolve8(filter_x);

   if (filter_taps == 2) {
     convolve8_horiz_2tap_neon(src + 3, src_stride, dst, dst_stride, filter_x, w,
                               h);
   } else if (filter_taps == 4) {
     convolve8_horiz_4tap_neon_dotprod(src + 2, src_stride, dst, dst_stride,
                                       filter_x, w, h);
   } else {
     convolve8_horiz_8tap_neon_dotprod(src, src_stride, dst, dst_stride,
                                       filter_x, w, h);
   }
 }

 static inline void transpose_concat_4x4(int8x8_t a0, int8x8_t a1, int8x8_t a2,
                                         int8x8_t a3, int8x16_t *b) {
   // Transpose 8-bit elements and concatenate result rows as follows:
   // a0: 00, 01, 02, 03, XX, XX, XX, XX
   // a1: 10, 11, 12, 13, XX, XX, XX, XX
   // a2: 20, 21, 22, 23, XX, XX, XX, XX
   // a3: 30, 31, 32, 33, XX, XX, XX, XX
   //
   // b: 00, 10, 20, 30, 01, 11, 21, 31, 02, 12, 22, 32, 03, 13, 23, 33

   int8x16_t a0q = vcombine_s8(a0, vdup_n_s8(0));
   int8x16_t a1q = vcombine_s8(a1, vdup_n_s8(0));
   int8x16_t a2q = vcombine_s8(a2, vdup_n_s8(0));
   int8x16_t a3q = vcombine_s8(a3, vdup_n_s8(0));

   int8x16_t a01 = vzipq_s8(a0q, a1q).val[0];
   int8x16_t a23 = vzipq_s8(a2q, a3q).val[0];

   int16x8_t a0123 =
       vzipq_s16(vreinterpretq_s16_s8(a01), vreinterpretq_s16_s8(a23)).val[0];

   *b = vreinterpretq_s8_s16(a0123);
 }

 static inline void transpose_concat_8x4(int8x8_t a0, int8x8_t a1, int8x8_t a2,
                                         int8x8_t a3, int8x16_t *b0,
                                         int8x16_t *b1) {
   // Transpose 8-bit elements and concatenate result rows as follows:
   // a0: 00, 01, 02, 03, 04, 05, 06, 07
   // a1: 10, 11, 12, 13, 14, 15, 16, 17
   // a2: 20, 21, 22, 23, 24, 25, 26, 27
   // a3: 30, 31, 32, 33, 34, 35, 36, 37
   //
   // b0: 00, 10, 20, 30, 01, 11, 21, 31, 02, 12, 22, 32, 03, 13, 23, 33
   // b1: 04, 14, 24, 34, 05, 15, 25, 35, 06, 16, 26, 36, 07, 17, 27, 37

   int8x16_t a0q = vcombine_s8(a0, vdup_n_s8(0));
   int8x16_t a1q = vcombine_s8(a1, vdup_n_s8(0));
   int8x16_t a2q = vcombine_s8(a2, vdup_n_s8(0));
   int8x16_t a3q = vcombine_s8(a3, vdup_n_s8(0));

   int8x16_t a01 = vzipq_s8(a0q, a1q).val[0];
   int8x16_t a23 = vzipq_s8(a2q, a3q).val[0];

   int16x8x2_t a0123 =
       vzipq_s16(vreinterpretq_s16_s8(a01), vreinterpretq_s16_s8(a23));

   *b0 = vreinterpretq_s8_s16(a0123.val[0]);
   *b1 = vreinterpretq_s8_s16(a0123.val[1]);
 }

 static inline int16x4_t convolve8_4_v(const int8x16_t samples_lo,
                                       const int8x16_t samples_hi,
                                       const int8x8_t filters) {
   // The sample range transform and permutation are performed by the caller.

   // Accumulate into 128 * FILTER_WEIGHT to account for range transform.
   // (Divide by 2 since we halved the filter values.)
   int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
   int32x4_t sum = vdotq_lane_s32(acc, samples_lo, filters, 0);
   sum = vdotq_lane_s32(sum, samples_hi, filters, 1);

   // Further narrowing and packing is performed by the caller.
   return vmovn_s32(sum);
 }

 static inline uint8x8_t convolve8_8_v(const int8x16_t samples0_lo,
                                       const int8x16_t samples0_hi,
                                       const int8x16_t samples1_lo,
                                       const int8x16_t samples1_hi,
                                       const int8x8_t filters) {
   // The sample range transform and permutation are performed by the caller.

   // Accumulate into 128 * FILTER_WEIGHT to account for range transform.
   // (Divide by 2 since we halved the filter values.)
   int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
   // First 4 output values.
   int32x4_t sum0 = vdotq_lane_s32(acc, samples0_lo, filters, 0);
   sum0 = vdotq_lane_s32(sum0, samples0_hi, filters, 1);
   // Second 4 output values.
   int32x4_t sum1 = vdotq_lane_s32(acc, samples1_lo, filters, 0);
   sum1 = vdotq_lane_s32(sum1, samples1_hi, filters, 1);

   // Narrow and re-pack.
   int16x8_t sum = vcombine_s16(vmovn_s32(sum0), vmovn_s32(sum1));
   // We halved the filter values so -1 from right shift.
   return vqrshrun_n_s16(sum, FILTER_BITS - 1);
 }

 static inline void convolve8_vert_8tap_neon_dotprod(
     const uint8_t *src, ptrdiff_t src_stride, uint8_t *dst,
     ptrdiff_t dst_stride, const int16_t *filter_y, int w, int h) {
   // Filter values are even, so halve to reduce intermediate precision reqs.
   const int8x8_t filter = vshrn_n_s16(vld1q_s16(filter_y), 1);
   const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);
   int8x16x2_t samples_LUT;

   if (w == 4) {
     uint8x8_t t0, t1, t2, t3, t4, t5, t6;
     load_u8_8x7(src, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
     src += 7 * src_stride;

     // Clamp sample range to [-128, 127] for 8-bit signed dot product.
     int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
     int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
     int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
     int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
     int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
     int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
     int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

     // This operation combines a conventional transpose and the sample permute
     // (see horizontal case) required before computing the dot product.
     int8x16_t s0123, s1234, s2345, s3456;
     transpose_concat_4x4(s0, s1, s2, s3, &s0123);
     transpose_concat_4x4(s1, s2, s3, s4, &s1234);
     transpose_concat_4x4(s2, s3, s4, s5, &s2345);
     transpose_concat_4x4(s3, s4, s5, s6, &s3456);

     do {
       uint8x8_t t7, t8, t9, t10;
       load_u8_8x4(src, src_stride, &t7, &t8, &t9, &t10);

       int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
       int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
       int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
       int8x8_t s10 = vreinterpret_s8_u8(vsub_u8(t10, vdup_n_u8(128)));

       int8x16_t s4567, s5678, s6789, s78910;
       transpose_concat_4x4(s7, s8, s9, s10, &s78910);

       // Merge new data into block from previous iteration.
       samples_LUT.val[0] = s3456;
       samples_LUT.val[1] = s78910;
       s4567 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
       s5678 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
       s6789 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

       int16x4_t d0 = convolve8_4_v(s0123, s4567, filter);
       int16x4_t d1 = convolve8_4_v(s1234, s5678, filter);
       int16x4_t d2 = convolve8_4_v(s2345, s6789, filter);
       int16x4_t d3 = convolve8_4_v(s3456, s78910, filter);
       // We halved the filter values so -1 from right shift.
       uint8x8_t d01 = vqrshrun_n_s16(vcombine_s16(d0, d1), FILTER_BITS - 1);
       uint8x8_t d23 = vqrshrun_n_s16(vcombine_s16(d2, d3), FILTER_BITS - 1);

       store_u8x4_strided_x2(dst + 0 * dst_stride, dst_stride, d01);
       store_u8x4_strided_x2(dst + 2 * dst_stride, dst_stride, d23);

       // Prepare block for next iteration - re-using as much as possible.
       // Shuffle everything up four rows.
       s0123 = s4567;
       s1234 = s5678;
       s2345 = s6789;
       s3456 = s78910;

       src += 4 * src_stride;
       dst += 4 * dst_stride;
       h -= 4;
     } while (h != 0);
   } else {
     do {
       int height = h;
       const uint8_t *s = src;
       uint8_t *d = dst;

       uint8x8_t t0, t1, t2, t3, t4, t5, t6;
       load_u8_8x7(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
       s += 7 * src_stride;

       // Clamp sample range to [-128, 127] for 8-bit signed dot product.
       int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
       int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
       int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
       int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
       int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
       int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
       int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

       // This operation combines a conventional transpose and the sample permute
       // (see horizontal case) required before computing the dot product.
       int8x16_t s0123_lo, s0123_hi, s1234_lo, s1234_hi, s2345_lo, s2345_hi,
           s3456_lo, s3456_hi;
       transpose_concat_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);
       transpose_concat_8x4(s1, s2, s3, s4, &s1234_lo, &s1234_hi);
       transpose_concat_8x4(s2, s3, s4, s5, &s2345_lo, &s2345_hi);
       transpose_concat_8x4(s3, s4, s5, s6, &s3456_lo, &s3456_hi);

       do {
         uint8x8_t t7, t8, t9, t10;
         load_u8_8x4(s, src_stride, &t7, &t8, &t9, &t10);

         int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
         int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
         int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
         int8x8_t s10 = vreinterpret_s8_u8(vsub_u8(t10, vdup_n_u8(128)));

         int8x16_t s4567_lo, s4567_hi, s5678_lo, s5678_hi, s6789_lo, s6789_hi,
             s78910_lo, s78910_hi;
         transpose_concat_8x4(s7, s8, s9, s10, &s78910_lo, &s78910_hi);

         // Merge new data into block from previous iteration.
         samples_LUT.val[0] = s3456_lo;
         samples_LUT.val[1] = s78910_lo;
         s4567_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
         s5678_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
         s6789_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

         samples_LUT.val[0] = s3456_hi;
         samples_LUT.val[1] = s78910_hi;
         s4567_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
         s5678_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
         s6789_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

         uint8x8_t d0 =
             convolve8_8_v(s0123_lo, s4567_lo, s0123_hi, s4567_hi, filter);
         uint8x8_t d1 =
             convolve8_8_v(s1234_lo, s5678_lo, s1234_hi, s5678_hi, filter);
         uint8x8_t d2 =
             convolve8_8_v(s2345_lo, s6789_lo, s2345_hi, s6789_hi, filter);
         uint8x8_t d3 =
             convolve8_8_v(s3456_lo, s78910_lo, s3456_hi, s78910_hi, filter);

         store_u8_8x4(d, dst_stride, d0, d1, d2, d3);

         // Prepare block for next iteration - re-using as much as possible.
         // Shuffle everything up four rows.
         s0123_lo = s4567_lo;
         s0123_hi = s4567_hi;
         s1234_lo = s5678_lo;
         s1234_hi = s5678_hi;
         s2345_lo = s6789_lo;
         s2345_hi = s6789_hi;
         s3456_lo = s78910_lo;
         s3456_hi = s78910_hi;

         s += 4 * src_stride;
         d += 4 * dst_stride;
         height -= 4;
       } while (height != 0);
       src += 8;
       dst += 8;
       w -= 8;
     } while (w != 0);
   }
 }

 void aom_convolve8_vert_neon_dotprod(const uint8_t *src, ptrdiff_t src_stride,
                                      uint8_t *dst, ptrdiff_t dst_stride,
                                      const int16_t *filter_x, int x_step_q4,
                                      const int16_t *filter_y, int y_step_q4,
                                      int w, int h) {
   assert((intptr_t)dst % 4 == 0);
   assert(dst_stride % 4 == 0);

   (void)filter_x;
   (void)x_step_q4;
   (void)y_step_q4;

   src -= ((SUBPEL_TAPS / 2) - 1) * src_stride;

   int filter_taps = get_filter_taps_convolve8(filter_y);

   if (filter_taps == 2) {
     convolve8_vert_2tap_neon(src + 3 * src_stride, src_stride, dst, dst_stride,
                              filter_y, w, h);
   } else if (filter_taps == 4) {
     convolve8_vert_4tap_neon(src + 2 * src_stride, src_stride, dst, dst_stride,
                              filter_y, w, h);
   } else {
     convolve8_vert_8tap_neon_dotprod(src, src_stride, dst, dst_stride, filter_y,
                                      w, h);
   }
 }
	/*
	* Copyright (c) 2014 The WebM project authors. All rights reserved.
	* Copyright (c) 2023, Alliance for Open Media. All rights reserved.
	*
	* This source code is subject to the terms of the BSD 2 Clause License and
	* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
	* was not distributed with this source code in the LICENSE file, you can
	* obtain it at www.aomedia.org/license/software. If the Alliance for Open
	* Media Patent License 1.0 was not distributed with this source code in the
	* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
	*/

	#include <arm_neon.h>
	#include <assert.h>
	#include <string.h>

	#include "config/aom_config.h"
	#include "config/aom_dsp_rtcd.h"

	#include "aom/aom_integer.h"
	#include "aom_dsp/aom_dsp_common.h"
	#include "aom_dsp/aom_filter.h"
	#include "aom_dsp/arm/aom_convolve8_neon.h"
	#include "aom_dsp/arm/aom_filter.h"
	#include "aom_dsp/arm/mem_neon.h"
	#include "aom_dsp/arm/transpose_neon.h"
	#include "aom_ports/mem.h"

	// Filter values always sum to 128.
	#define FILTER_WEIGHT 128

	DECLARE_ALIGNED(16, static const uint8_t, kDotProdPermuteTbl[48]) = {
	0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6,
	4, 5, 6, 7, 5, 6, 7, 8, 6, 7, 8, 9, 7, 8, 9, 10,
	8, 9, 10, 11, 9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14
	};

	DECLARE_ALIGNED(16, static const uint8_t, kDotProdMergeBlockTbl[48]) = {
	// Shift left and insert new last column in transposed 4x4 block.
	1, 2, 3, 16, 5, 6, 7, 20, 9, 10, 11, 24, 13, 14, 15, 28,
	// Shift left and insert two new columns in transposed 4x4 block.
	2, 3, 16, 17, 6, 7, 20, 21, 10, 11, 24, 25, 14, 15, 28, 29,
	// Shift left and insert three new columns in transposed 4x4 block.
	3, 16, 17, 18, 7, 20, 21, 22, 11, 24, 25, 26, 15, 28, 29, 30
	};

	static inline int16x4_t convolve8_4_h(const uint8x16_t samples,
	const int8x8_t filters,
	const uint8x16x2_t permute_tbl) {
	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t samples_128 =
	vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

	// Permute samples ready for dot product.
	// { 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6 }
	// { 4, 5, 6, 7, 5, 6, 7, 8, 6, 7, 8, 9, 7, 8, 9, 10 }
	int8x16_t perm_samples[2] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
	vqtbl1q_s8(samples_128, permute_tbl.val[1]) };

	// Accumulate into 128 * FILTER_WEIGHT to account for range transform.
	// (Divide by 2 since we halved the filter values.)
	int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
	int32x4_t sum = vdotq_lane_s32(acc, perm_samples[0], filters, 0);
	sum = vdotq_lane_s32(sum, perm_samples[1], filters, 1);

	// Further narrowing and packing is performed by the caller.
	return vmovn_s32(sum);
	}

	static inline uint8x8_t convolve8_8_h(const uint8x16_t samples,
	const int8x8_t filters,
	const uint8x16x3_t permute_tbl) {
	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t samples_128 =
	vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

	// Permute samples ready for dot product.
	// { 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6 }
	// { 4, 5, 6, 7, 5, 6, 7, 8, 6, 7, 8, 9, 7, 8, 9, 10 }
	// { 8, 9, 10, 11, 9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14 }
	int8x16_t perm_samples[3] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
	vqtbl1q_s8(samples_128, permute_tbl.val[1]),
	vqtbl1q_s8(samples_128, permute_tbl.val[2]) };

	// Accumulate into 128 * FILTER_WEIGHT to account for range transform.
	// (Divide by 2 since we halved the filter values.)
	int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
	// First 4 output values.
	int32x4_t sum0 = vdotq_lane_s32(acc, perm_samples[0], filters, 0);
	sum0 = vdotq_lane_s32(sum0, perm_samples[1], filters, 1);
	// Second 4 output values.
	int32x4_t sum1 = vdotq_lane_s32(acc, perm_samples[1], filters, 0);
	sum1 = vdotq_lane_s32(sum1, perm_samples[2], filters, 1);

	// Narrow and re-pack.
	int16x8_t sum = vcombine_s16(vmovn_s32(sum0), vmovn_s32(sum1));
	// We halved the filter values so -1 from right shift.
	return vqrshrun_n_s16(sum, FILTER_BITS - 1);
	}

	static inline void convolve8_horiz_8tap_neon_dotprod(
	const uint8_t src, ptrdiff_t src_stride, uint8_t dst,
	ptrdiff_t dst_stride, const int16_t *filter_x, int w, int h) {
	// Filter values are even, so halve to reduce intermediate precision reqs.
	const int8x8_t filter = vshrn_n_s16(vld1q_s16(filter_x), 1);

	if (w == 4) {
	const uint8x16x2_t perm_tbl = vld1q_u8_x2(kDotProdPermuteTbl);
	do {
	uint8x16_t s0, s1, s2, s3;
	load_u8_16x4(src, src_stride, &s0, &s1, &s2, &s3);

	int16x4_t d0 = convolve8_4_h(s0, filter, perm_tbl);
	int16x4_t d1 = convolve8_4_h(s1, filter, perm_tbl);
	int16x4_t d2 = convolve8_4_h(s2, filter, perm_tbl);
	int16x4_t d3 = convolve8_4_h(s3, filter, perm_tbl);
	// We halved the filter values so -1 from right shift.
	uint8x8_t d01 = vqrshrun_n_s16(vcombine_s16(d0, d1), FILTER_BITS - 1);
	uint8x8_t d23 = vqrshrun_n_s16(vcombine_s16(d2, d3), FILTER_BITS - 1);

	store_u8x4_strided_x2(dst + 0 * dst_stride, dst_stride, d01);
	store_u8x4_strided_x2(dst + 2 * dst_stride, dst_stride, d23);

	src += 4 * src_stride;
	dst += 4 * dst_stride;
	h -= 4;
	} while (h > 0);
	} else {
	const uint8x16x3_t perm_tbl = vld1q_u8_x3(kDotProdPermuteTbl);

	do {
	int width = w;
	const uint8_t *s = src;
	uint8_t *d = dst;
	do {
	uint8x16_t s0, s1, s2, s3;
	load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

	uint8x8_t d0 = convolve8_8_h(s0, filter, perm_tbl);
	uint8x8_t d1 = convolve8_8_h(s1, filter, perm_tbl);
	uint8x8_t d2 = convolve8_8_h(s2, filter, perm_tbl);
	uint8x8_t d3 = convolve8_8_h(s3, filter, perm_tbl);

	store_u8_8x4(d, dst_stride, d0, d1, d2, d3);

	s += 8;
	d += 8;
	width -= 8;
	} while (width != 0);
	src += 4 * src_stride;
	dst += 4 * dst_stride;
	h -= 4;
	} while (h > 0);
	}
	}

	static inline int16x4_t convolve4_4_h(const uint8x16_t samples,
	const int8x8_t filters,
	const uint8x16_t permute_tbl) {
	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t samples_128 =
	vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

	// Permute samples ready for dot product.
	// { 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6 }
	int8x16_t perm_samples = vqtbl1q_s8(samples_128, permute_tbl);

	// Accumulate into 128 * FILTER_WEIGHT to account for range transform.
	// (Divide by 2 since we halved the filter values.)
	int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
	int32x4_t sum = vdotq_lane_s32(acc, perm_samples, filters, 0);

	// Further narrowing and packing is performed by the caller.
	return vmovn_s32(sum);
	}

	static inline uint8x8_t convolve4_8_h(const uint8x16_t samples,
	const int8x8_t filters,
	const uint8x16x2_t permute_tbl) {
	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t samples_128 =
	vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

	// Permute samples ready for dot product.
	// { 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6 }
	// { 4, 5, 6, 7, 5, 6, 7, 8, 6, 7, 8, 9, 7, 8, 9, 10 }
	int8x16_t perm_samples[2] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
	vqtbl1q_s8(samples_128, permute_tbl.val[1]) };

	// Accumulate into 128 * FILTER_WEIGHT to account for range transform.
	// (Divide by 2 since we halved the filter values.)
	int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
	// First 4 output values.
	int32x4_t sum0 = vdotq_lane_s32(acc, perm_samples[0], filters, 0);
	// Second 4 output values.
	int32x4_t sum1 = vdotq_lane_s32(acc, perm_samples[1], filters, 0);

	// Narrow and re-pack.
	int16x8_t sum = vcombine_s16(vmovn_s32(sum0), vmovn_s32(sum1));
	// We halved the filter values so -1 from right shift.
	return vqrshrun_n_s16(sum, FILTER_BITS - 1);
	}

	static inline void convolve8_horiz_4tap_neon_dotprod(
	const uint8_t src, ptrdiff_t src_stride, uint8_t dst,
	ptrdiff_t dst_stride, const int16_t *filter_x, int width, int height) {
	const int16x4_t x_filter = vld1_s16(filter_x + 2);
	// All 4-tap and bilinear filter values are even, so halve them to reduce
	// intermediate precision requirements.
	const int8x8_t filter = vshrn_n_s16(vcombine_s16(x_filter, vdup_n_s16(0)), 1);

	if (width == 4) {
	const uint8x16_t permute_tbl = vld1q_u8(kDotProdPermuteTbl);

	do {
	uint8x16_t s0, s1, s2, s3;
	load_u8_16x4(src, src_stride, &s0, &s1, &s2, &s3);

	int16x4_t t0 = convolve4_4_h(s0, filter, permute_tbl);
	int16x4_t t1 = convolve4_4_h(s1, filter, permute_tbl);
	int16x4_t t2 = convolve4_4_h(s2, filter, permute_tbl);
	int16x4_t t3 = convolve4_4_h(s3, filter, permute_tbl);
	// We halved the filter values so -1 from right shift.
	uint8x8_t d01 = vqrshrun_n_s16(vcombine_s16(t0, t1), FILTER_BITS - 1);
	uint8x8_t d23 = vqrshrun_n_s16(vcombine_s16(t2, t3), FILTER_BITS - 1);

	store_u8x4_strided_x2(dst + 0 * dst_stride, dst_stride, d01);
	store_u8x4_strided_x2(dst + 2 * dst_stride, dst_stride, d23);

	src += 4 * src_stride;
	dst += 4 * dst_stride;
	height -= 4;
	} while (height > 0);
	} else {
	const uint8x16x2_t permute_tbl = vld1q_u8_x2(kDotProdPermuteTbl);

	do {
	const uint8_t *s = src;
	uint8_t *d = dst;
	int w = width;

	do {
	uint8x16_t s0, s1, s2, s3;
	load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

	uint8x8_t d0 = convolve4_8_h(s0, filter, permute_tbl);
	uint8x8_t d1 = convolve4_8_h(s1, filter, permute_tbl);
	uint8x8_t d2 = convolve4_8_h(s2, filter, permute_tbl);
	uint8x8_t d3 = convolve4_8_h(s3, filter, permute_tbl);

	store_u8_8x4(d, dst_stride, d0, d1, d2, d3);

	s += 8;
	d += 8;
	w -= 8;
	} while (w != 0);
	src += 4 * src_stride;
	dst += 4 * dst_stride;
	height -= 4;
	} while (height > 0);
	}
	}

	void aom_convolve8_horiz_neon_dotprod(const uint8_t *src, ptrdiff_t src_stride,
	uint8_t *dst, ptrdiff_t dst_stride,
	const int16_t *filter_x, int x_step_q4,
	const int16_t *filter_y, int y_step_q4,
	int w, int h) {
	assert((intptr_t)dst % 4 == 0);
	assert(dst_stride % 4 == 0);

	(void)x_step_q4;
	(void)filter_y;
	(void)y_step_q4;

	src -= ((SUBPEL_TAPS / 2) - 1);

	int filter_taps = get_filter_taps_convolve8(filter_x);

	if (filter_taps == 2) {
	convolve8_horiz_2tap_neon(src + 3, src_stride, dst, dst_stride, filter_x, w,
	h);
	} else if (filter_taps == 4) {
	convolve8_horiz_4tap_neon_dotprod(src + 2, src_stride, dst, dst_stride,
	filter_x, w, h);
	} else {
	convolve8_horiz_8tap_neon_dotprod(src, src_stride, dst, dst_stride,
	filter_x, w, h);
	}
	}

	static inline void transpose_concat_4x4(int8x8_t a0, int8x8_t a1, int8x8_t a2,
	int8x8_t a3, int8x16_t *b) {
	// Transpose 8-bit elements and concatenate result rows as follows:
	// a0: 00, 01, 02, 03, XX, XX, XX, XX
	// a1: 10, 11, 12, 13, XX, XX, XX, XX
	// a2: 20, 21, 22, 23, XX, XX, XX, XX
	// a3: 30, 31, 32, 33, XX, XX, XX, XX
	//
	// b: 00, 10, 20, 30, 01, 11, 21, 31, 02, 12, 22, 32, 03, 13, 23, 33

	int8x16_t a0q = vcombine_s8(a0, vdup_n_s8(0));
	int8x16_t a1q = vcombine_s8(a1, vdup_n_s8(0));
	int8x16_t a2q = vcombine_s8(a2, vdup_n_s8(0));
	int8x16_t a3q = vcombine_s8(a3, vdup_n_s8(0));

	int8x16_t a01 = vzipq_s8(a0q, a1q).val[0];
	int8x16_t a23 = vzipq_s8(a2q, a3q).val[0];

	int16x8_t a0123 =
	vzipq_s16(vreinterpretq_s16_s8(a01), vreinterpretq_s16_s8(a23)).val[0];

	*b = vreinterpretq_s8_s16(a0123);
	}

	static inline void transpose_concat_8x4(int8x8_t a0, int8x8_t a1, int8x8_t a2,
	int8x8_t a3, int8x16_t *b0,
	int8x16_t *b1) {
	// Transpose 8-bit elements and concatenate result rows as follows:
	// a0: 00, 01, 02, 03, 04, 05, 06, 07
	// a1: 10, 11, 12, 13, 14, 15, 16, 17
	// a2: 20, 21, 22, 23, 24, 25, 26, 27
	// a3: 30, 31, 32, 33, 34, 35, 36, 37
	//
	// b0: 00, 10, 20, 30, 01, 11, 21, 31, 02, 12, 22, 32, 03, 13, 23, 33
	// b1: 04, 14, 24, 34, 05, 15, 25, 35, 06, 16, 26, 36, 07, 17, 27, 37

	int8x16_t a0q = vcombine_s8(a0, vdup_n_s8(0));
	int8x16_t a1q = vcombine_s8(a1, vdup_n_s8(0));
	int8x16_t a2q = vcombine_s8(a2, vdup_n_s8(0));
	int8x16_t a3q = vcombine_s8(a3, vdup_n_s8(0));

	int8x16_t a01 = vzipq_s8(a0q, a1q).val[0];
	int8x16_t a23 = vzipq_s8(a2q, a3q).val[0];

	int16x8x2_t a0123 =
	vzipq_s16(vreinterpretq_s16_s8(a01), vreinterpretq_s16_s8(a23));

	*b0 = vreinterpretq_s8_s16(a0123.val[0]);
	*b1 = vreinterpretq_s8_s16(a0123.val[1]);
	}

	static inline int16x4_t convolve8_4_v(const int8x16_t samples_lo,
	const int8x16_t samples_hi,
	const int8x8_t filters) {
	// The sample range transform and permutation are performed by the caller.

	// Accumulate into 128 * FILTER_WEIGHT to account for range transform.
	// (Divide by 2 since we halved the filter values.)
	int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
	int32x4_t sum = vdotq_lane_s32(acc, samples_lo, filters, 0);
	sum = vdotq_lane_s32(sum, samples_hi, filters, 1);

	// Further narrowing and packing is performed by the caller.
	return vmovn_s32(sum);
	}

	static inline uint8x8_t convolve8_8_v(const int8x16_t samples0_lo,
	const int8x16_t samples0_hi,
	const int8x16_t samples1_lo,
	const int8x16_t samples1_hi,
	const int8x8_t filters) {
	// The sample range transform and permutation are performed by the caller.

	// Accumulate into 128 * FILTER_WEIGHT to account for range transform.
	// (Divide by 2 since we halved the filter values.)
	int32x4_t acc = vdupq_n_s32(128 * FILTER_WEIGHT / 2);
	// First 4 output values.
	int32x4_t sum0 = vdotq_lane_s32(acc, samples0_lo, filters, 0);
	sum0 = vdotq_lane_s32(sum0, samples0_hi, filters, 1);
	// Second 4 output values.
	int32x4_t sum1 = vdotq_lane_s32(acc, samples1_lo, filters, 0);
	sum1 = vdotq_lane_s32(sum1, samples1_hi, filters, 1);

	// Narrow and re-pack.
	int16x8_t sum = vcombine_s16(vmovn_s32(sum0), vmovn_s32(sum1));
	// We halved the filter values so -1 from right shift.
	return vqrshrun_n_s16(sum, FILTER_BITS - 1);
	}

	static inline void convolve8_vert_8tap_neon_dotprod(
	const uint8_t src, ptrdiff_t src_stride, uint8_t dst,
	ptrdiff_t dst_stride, const int16_t *filter_y, int w, int h) {
	// Filter values are even, so halve to reduce intermediate precision reqs.
	const int8x8_t filter = vshrn_n_s16(vld1q_s16(filter_y), 1);
	const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);
	int8x16x2_t samples_LUT;

	if (w == 4) {
	uint8x8_t t0, t1, t2, t3, t4, t5, t6;
	load_u8_8x7(src, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
	src += 7 * src_stride;

	// Clamp sample range to [-128, 127] for 8-bit signed dot product.
	int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
	int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
	int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
	int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
	int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
	int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
	int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

	// This operation combines a conventional transpose and the sample permute
	// (see horizontal case) required before computing the dot product.
	int8x16_t s0123, s1234, s2345, s3456;
	transpose_concat_4x4(s0, s1, s2, s3, &s0123);
	transpose_concat_4x4(s1, s2, s3, s4, &s1234);
	transpose_concat_4x4(s2, s3, s4, s5, &s2345);
	transpose_concat_4x4(s3, s4, s5, s6, &s3456);

	do {
	uint8x8_t t7, t8, t9, t10;
	load_u8_8x4(src, src_stride, &t7, &t8, &t9, &t10);

	int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
	int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
	int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
	int8x8_t s10 = vreinterpret_s8_u8(vsub_u8(t10, vdup_n_u8(128)));

	int8x16_t s4567, s5678, s6789, s78910;
	transpose_concat_4x4(s7, s8, s9, s10, &s78910);

	// Merge new data into block from previous iteration.
	samples_LUT.val[0] = s3456;
	samples_LUT.val[1] = s78910;
	s4567 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
	s5678 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
	s6789 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

	int16x4_t d0 = convolve8_4_v(s0123, s4567, filter);
	int16x4_t d1 = convolve8_4_v(s1234, s5678, filter);
	int16x4_t d2 = convolve8_4_v(s2345, s6789, filter);
	int16x4_t d3 = convolve8_4_v(s3456, s78910, filter);
	// We halved the filter values so -1 from right shift.
	uint8x8_t d01 = vqrshrun_n_s16(vcombine_s16(d0, d1), FILTER_BITS - 1);
	uint8x8_t d23 = vqrshrun_n_s16(vcombine_s16(d2, d3), FILTER_BITS - 1);

	store_u8x4_strided_x2(dst + 0 * dst_stride, dst_stride, d01);
	store_u8x4_strided_x2(dst + 2 * dst_stride, dst_stride, d23);

	// Prepare block for next iteration - re-using as much as possible.
	// Shuffle everything up four rows.
	s0123 = s4567;
	s1234 = s5678;
	s2345 = s6789;
	s3456 = s78910;

	src += 4 * src_stride;
	dst += 4 * dst_stride;
	h -= 4;
	} while (h != 0);
	} else {
	do {
	int height = h;
	const uint8_t *s = src;
	uint8_t *d = dst;

	uint8x8_t t0, t1, t2, t3, t4, t5, t6;
	load_u8_8x7(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
	s += 7 * src_stride;

	// Clamp sample range to [-128, 127] for 8-bit signed dot product.
	int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
	int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
	int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
	int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
	int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
	int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
	int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

	// This operation combines a conventional transpose and the sample permute
	// (see horizontal case) required before computing the dot product.
	int8x16_t s0123_lo, s0123_hi, s1234_lo, s1234_hi, s2345_lo, s2345_hi,
	s3456_lo, s3456_hi;
	transpose_concat_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);
	transpose_concat_8x4(s1, s2, s3, s4, &s1234_lo, &s1234_hi);
	transpose_concat_8x4(s2, s3, s4, s5, &s2345_lo, &s2345_hi);
	transpose_concat_8x4(s3, s4, s5, s6, &s3456_lo, &s3456_hi);

	do {
	uint8x8_t t7, t8, t9, t10;
	load_u8_8x4(s, src_stride, &t7, &t8, &t9, &t10);

	int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
	int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
	int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
	int8x8_t s10 = vreinterpret_s8_u8(vsub_u8(t10, vdup_n_u8(128)));

	int8x16_t s4567_lo, s4567_hi, s5678_lo, s5678_hi, s6789_lo, s6789_hi,
	s78910_lo, s78910_hi;
	transpose_concat_8x4(s7, s8, s9, s10, &s78910_lo, &s78910_hi);

	// Merge new data into block from previous iteration.
	samples_LUT.val[0] = s3456_lo;
	samples_LUT.val[1] = s78910_lo;
	s4567_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
	s5678_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
	s6789_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

	samples_LUT.val[0] = s3456_hi;
	samples_LUT.val[1] = s78910_hi;
	s4567_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
	s5678_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
	s6789_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

	uint8x8_t d0 =
	convolve8_8_v(s0123_lo, s4567_lo, s0123_hi, s4567_hi, filter);
	uint8x8_t d1 =
	convolve8_8_v(s1234_lo, s5678_lo, s1234_hi, s5678_hi, filter);
	uint8x8_t d2 =
	convolve8_8_v(s2345_lo, s6789_lo, s2345_hi, s6789_hi, filter);
	uint8x8_t d3 =
	convolve8_8_v(s3456_lo, s78910_lo, s3456_hi, s78910_hi, filter);

	store_u8_8x4(d, dst_stride, d0, d1, d2, d3);

	// Prepare block for next iteration - re-using as much as possible.
	// Shuffle everything up four rows.
	s0123_lo = s4567_lo;
	s0123_hi = s4567_hi;
	s1234_lo = s5678_lo;
	s1234_hi = s5678_hi;
	s2345_lo = s6789_lo;
	s2345_hi = s6789_hi;
	s3456_lo = s78910_lo;
	s3456_hi = s78910_hi;

	s += 4 * src_stride;
	d += 4 * dst_stride;
	height -= 4;
	} while (height != 0);
	src += 8;
	dst += 8;
	w -= 8;
	} while (w != 0);
	}
	}

	void aom_convolve8_vert_neon_dotprod(const uint8_t *src, ptrdiff_t src_stride,
	uint8_t *dst, ptrdiff_t dst_stride,
	const int16_t *filter_x, int x_step_q4,
	const int16_t *filter_y, int y_step_q4,
	int w, int h) {
	assert((intptr_t)dst % 4 == 0);
	assert(dst_stride % 4 == 0);

	(void)filter_x;
	(void)x_step_q4;
	(void)y_step_q4;

	src -= ((SUBPEL_TAPS / 2) - 1) * src_stride;

	int filter_taps = get_filter_taps_convolve8(filter_y);

	if (filter_taps == 2) {
	convolve8_vert_2tap_neon(src + 3 * src_stride, src_stride, dst, dst_stride,
	filter_y, w, h);
	} else if (filter_taps == 4) {
	convolve8_vert_4tap_neon(src + 2 * src_stride, src_stride, dst, dst_stride,
	filter_y, w, h);
	} else {
	convolve8_vert_8tap_neon_dotprod(src, src_stride, dst, dst_stride, filter_y,
	w, h);
	}
	}